Is there any documentation out there on sending logs from containers in K8s to an external ELK cluster running on EC2 instances?
We're in the process of trying to Kubernetes set up and I'm trying to figure out how to get the logging to work correctly. We already have an ELK stack setup on EC2 for current versions of the application but most of the documentation out there seems to be referring to ELK as it's deployed to the K8s cluster.
I am also working on the same cause.
First you should know what driver is being used by your docker containers to manage the logs (json driver/ journald etc - read here).
After that you should use some log collector in your architecture to send the logs to the Logstash endpoint. You can use filebeat/fluent bit. They are light weight alternatives to logstash/fluentd respectively. You must use one of them and not directly send your logs to logstash via syslog since these log shippers have a special functionality of enriching your logs with kubernetes metadata of the respective containers.
There might be lot of challenges after that. Parsing log data (multiline logs for example) etc. For an efficient pipeline, it’s better to do most of the work (i.e. extracting the date object from the logs etc) at the log sender side, than using the common logstash for this purpose that might be a bottle-neck.
Note that in case the container logs are not sent to stdout/stderr but written else-where, you might need to run filebeat/fluent-bit as side-car with your containers.
As for the links for documentation are concerned, I myself didn’t find anything documented in a single place on this, but the keywords that I mentioned over, reading about them I got to know many things.
Hope this helps.